It seems that the prior art was not interested in EUP including a unsaturated group at only one of its chain ends; but said products can be useful in the preparation of polymers having special properties convenient for certain particular uses. On the other hand, there are found in the technical literature references to the oligomers, polyesters and polyamides that include an unsaturated group at each one of the two ends of the chain (U.S. Pat. No. 3,483,104 and Japanese patent No. 51-125017); according to the prior art, they are most often prepared in solution, or using an unsaturated acid chloride or acid anhydride. This process is not economical and the oligomers of the prior art that have thus been prepared have low molecular weights that limit their applications.
This invention overcomes the above noted deficiency of the prior art; it makes possible the economical preparation, without a solvent and without using an acid chloride or anhydride, in a molten medium, of EUP that possess at only one end of their polymeric chain, an unsaturated group. The invention thus brings to the industry new products that are specially useful as thermosetting molding materials, additives for polyamide powders, impregnating resins, and the like. The polymers according to the invention are particularly suited for the preparation of interesting thermoplastic materials by grafting of said EUP on olefins or copolyolefins.